The doctor should investigate your acne as there may be an underlying hormonal cause such as PCOS that needs treatment.
There are many things that can be done to help acne. A course of oral antibiotics such as Oxytetracycline or Erythromycin would be useful. A topical synthetic retinoid such as topical Isotretinoin or Differin will also help. If tests show that you have high levels of male hormones in your body an oestrogen or anti-androgen medication would help. I suggest one more visit to the doctor, armed with this information.
Over the counter products are of limited benefit compared to prescription treatments when acne is this severe, and you shoud be realistic about their usefulness. That said, the best non-prescription acne gel I have found is Freederm.
Don't be reluctant to wear make-up to a special occasion, there are lots of useful full coverage foundations which don't appear mask like. Estee Lauder Maximum coverage foundation is very good. Alternatively, could you wear a pashmina or shawl?